Electric fuse for projectiles



May 17, 1932. H. RUHLEMANN ELECTRIC FUSE FOR PROJECTILES Original Filed June 22. 1927 Patented May 17, 932

HERBERT RfiI-ILEMANN, OF SOM MERDA, GERMANY, ASSIGNOR 'I'O RHEINISCHE METALL- WAAREN- UNI) MASCHINENFABRIK, OI DUSSELDORF-DERENDORFF, GERMANY ELECTRIC FUSE FOR PROJEGTILES Original application filed June 22, 1927, Serial No. 200,683, and in Germanvlune 26, 1926. Divided an this application filed March 3, 1930. Serial No. 432,865.

The resent application is a divisio of apcontact g to a metal strip 23 which is stretched plicant s prior application Serial No. 2 0,683, across the path of the ma et a and over filed June 22, 1927, now Patent No. 1,755,023, contact k to theother tin-foil of the condenser dated April 15, 1930, and relates to an elecf. The conductors 0,9, 71 and k are insulated tric fuse in which a condenser acts as a storage means from an electric source to-supply the ignition current for an electrical igniting device. g

The inventionmakes possible, by the use of such a condenser as an igmtion'cunrnt storage means, to produce an electric fuse, which is extremely sensitive and quick to operate, having a simple compact con-' struction for projectiles, mines, etc. Such condenser arrangement in an electric time fuse also permits the stored current to be used at the same time for an impact ignition so that a simple and electrically-operated double igniter is produced. For this purpose, a contact is connected in series with the electric ignition means and the condenser.

In the accompanying drawings, some modifications of electric fuses according to the invention are shown by way of example in connection with an impact-fuse. 1

Figure 1 shows a longitudinal section of a fuse according to the invention,

Fig. 2 is a cross section on the line A-B of Fig. 1,

- Fig. 3 shows diagrammatically the electrical connections, and r r Fig. 4 is adetail of the modification shown in Fig. 3.

In the longitudinal axis of the projectile, a permanent magnet a is arranged shiftable' in the longitudinal direction. The magnet a is held in the head of the; projectile in its front end position by means of a locking device of known construction, for instance, by the lock spring I). Around the magnet a is arranged a coil body 0 wound with several turns d of insulated copperwire. 'The coil body. 0 is fixed in the head of the projectile. Thetwo ends of the turns a! are connected- .to a condenser f which, for instance, may be from the body of the projectile.

The tin-foil of the condenser 7 connected to the contact e is also connected to the insulated conductor Z. Connected to this conductor at .m is the one end of a thin resistance wire 0 embedded in the priming-composition n and servingas heating or ignition wire.

This wire may, in the manner of the filament of an incandescent lamp, be wound or bent in a spiral or coil or in zigzag. Instead of an ordinary resistance wire, awire of silit or of a similar material may be used. The other end of the resistance wire is connected at p to the contact 9 which in turn slides upon the surface of a resistance 1' arranged in a circle. The resistance r is insulated and unmovably arranged in a ring 8 which is rotatably and adjustably mounted in the head of the projectile. The ring 8 has in this construction the function of the usual composition ring in burning-fuses. The one end of the resistance 1 which, in the example illustrated, forms an annularly bent, helically wound wire is free, whereas its other end is electrically connected to the head of the projectile by means of a screw t.

When firing the projectile, the magnet a by theinertia of its mass comes free from' the locking springs b and moves to the rear in the head of the projectile. During this movement, the lines of force of the magnet intersect the turns of the coil (tend generate in the latter an induction current by which the condenser f is loaded, as this coil d, as stated above, is connected to-both coatings of the condenser f. Shortly before reaching its rear end position the magnet-a impacts upon the metal strip 2' and bends same in the middle. Hereby the one end of the metal strip is withdrawn fromthe contact g. The.

circuit of the coil d across the condenser f is opened and the loaded condenser f is disconnected from the coil d.

At the same time. the circuit of the condenser across the heating wire 0 of the priming-composition n is closed by the metal strip 71 bent in its middle by the magnet to such an extent as to make contact with the rear closing nut of the head of the projectile. Thereby the current flows from the one tinfoil of the condenser f through the conductor Z and the screw m to the heating wire -0 from which the current passes through the screw 17 and thecontact g to the resistance 1'. According to the angular position of the ring 8 in the head of the projectile, the current flows therethrough a greater or smallernumber of wire turns, i. e. a greater or smaller length of the resistance wire itself until it passes at the end at t into the body ofthe projectile and returns through the latter to the metal strip z and from there to the contact is and the other tin-foil of the condenser f. Ac-

cording to the height of the resistance in form' of the wire windings adjusted in the resistance 1" more or less current will flow in the circuit and therefore also through the I heating wire 0 of the priming-composition n,

The heating wire 0 furnishes an amount .26 of heat according to the Joule-law of.

Q=0.24 l rt g; cal., that is to say, the

amount of heat generated depends upon the strength of thecurrent.

As' a quite definite degree of heat is required for igniting the prlming-composition, the ignition will be effected with a current of low strength after a longer period of action only, whereas with a high strength of current ignition takes place after'a short period of time already. By means of the regulating resistance 7', the-strength of 'the current and thereby the desired time necessaryfor caus ing ignition may be adjusted. The ring 8 is for this purpose, as the priming-composition of burning-fuses, provided with a scale indicating the ignition time points.,afterfiring which together with a mark at the head of the projectile permits to read off the ignition time adjuste In the construction shown in Fig. 3, the

magnet a, as in the construction above described, on firing of the projectile moves :through'the coil d and generates inthelatter detonation point is at 400 C., the ignition wire is preheated by this circuit to a temperature of about 350 C. At theend ofthe movement of the magnet a with regard to the coil d, the latter is disconnected from the condenser f and, moreover, the circuit for preheating the ignition wire is opened. The

If, for instance, the

metal strip i then comes into the position shown in dotted lines and hereby closes the condenser 7 over the ignition wire 0 and the resistance 1- adjustable by the moving contact u. The discharge of the condenser f then takes place from the one tin-foil A: through the points 3, 13, 14, 15, 10, 11, 12, (Ho its second coating 5. This current furnished by the condenser f durin the flight of the projectile is proportione by the resistance r in such a manner that it efiects the remaining heating of the ignition wire from 350 C. to thetemperature of 450 C. which corresponds to the detonation point of the priming-composition and therefore the ignition of the latter after the lapse of the time adjusted at the indicating device of the resistance 1'.

Fig. 4 illustrates a device which makes the electric time-fuse described above also suitable as an impact-fuse. If during the flight of the projectile the priming-composition will not be caused toignite at the adjusted ignition time point, the resiliently mounted contact piece '0 will, when the projectile impacts upon an aim, be thrown forward by the inertia of its mass. Hereby the contact piece o is pressed against a fixed contact w and short-circuits resistance 1'. The rest of the condenser load may hereby at once discharge Without resistance through the priming-composition which efi'ects the ignition of the atter.

. According to another arrangement not shown an automatically acting contact device may be used by means of which, when theprojectile impacts upon an aim, the electric energy generated by the movement of the. magnet a in the induction coil is passed through the ignition wire 0, so that the ignition of the priming-composition is caused.

The present invention is a division of ap- Y plication Serial No. 200,683, filed June 22 1927, Patent No. 1,755,023. v 7

What I claim as my invention is An electric impact-fuse for projectiles comprising a source of current, a condenser for V storing current furnished b saidsource of current'and an electric igniting means and a contact adapted to be closed. on impact, said igniting means and said contact being connected in series with, the discharge circuit of said condenser.

In testimony whereof I afiix my signature.

HERBERT RUHLEMANN, 

